Antibacterial Activity of Tanshinones from the Root of Salvia miltiorrhiza against Methicillin-resistant Staphylococcus aureus

Objective: Methicillin-resistant Staphylococcus aureus (MRSA) has been emerging worldwide as one of the most important problems in dental and medical fields, especially acute oral infection. Therefore, new agents are needed to treat the MRSA. To investigate the antibacterial agents against MRSA from acute oral infection, several natural product extracts were screened. The active compounds, tanshinones (dihydrotanshinone ¥°, crytotanshinone, tanshinone¥°, and tanshinone ¥±A) from Salvia miltiorrhiza(S. miltiorrhiza) were isolated successively through the screening system and various purification methods. Method: S. miltiorrhiza was extracted with 80% EtOH. The extract was suspended in H₂O and partitioned with CHCl₃, EtOAC, and n-BuOH in sequence. The CHCl₃ fraction showed remarkable antibacterial activity against MRSA. Column chromatography of the most active fraction on silica gel and recycling prep-HPLC gave purified compounds. The structure of compounds was identified by MS, ¹H-NMR, and ¹³C-NMR. Result: The CHCl₃ fraction from solvent partition possessed greater antibacterial potential than other fractions. The fraction were obtained from column chromatography with silica gel had antibacterial activity against MRSA, and the fraction was separated by recycling prep-HPLC to purified compounds. Their structures were identified as dihydrotanshinone ¥°, crytotanshinone, tanshinone¥°, and tanshinone ¥±A by MS, ¹H-NMR, and ¹³C-NMR. The minimum inhibitory concentrations (MICs) of tanshinones to the S. aureus (MRSA and MSSA) ranged from 2 to 64 mg/ml. Among tanshinones, dihydrotanshinone ¥° and tanshinone¥° showed significant antibacterial activity aganist MRSA (2 mg/ml). Conclusion: These results suggest that tanshinones might have the antibacterial activity against MRSA from acute oral infection. Supported by a grant of No. R01-2001-00133-0 from KOSEA.